Method of steelmaking



June 1967 R. s. MILTENBERGER ETAL 3,323,906

METHOD OF STEELMAK ING Filed Aug. 12. 1964 INVENTORS ROBERT S. MILTENBERGER RICHARD B. MORGAN RALPH DUFFETT JR.

WILLIAM E. SHEPHER A TTOR NE Y5 United States Patent 3,323,906 METHGD OF STEELMAKING Robert S. Miltenherger, Grosse Ile, MiclL, Richard B. Morgan, Weirton, W. Va., and Ralph Dutfett, Jr., Grosse lie, and Wiliiam E. Shepherd, Allen Park, Mich., assignors to National Steel Corporation, a corporation of Delaware Filed Aug. 12, 1964, Ser. No. 389,094 4 Claims. (Cl. 75-60) This invention relates to the refining of metals and more particularly to improvements on operation of basic oxygen furnaces for steelmaking.

In basic oxygen furnace steelmaking, scrap and molten metal are charged into a refractory lined vessel having a closed bottom and side walls converging inwardly at the top or nose to form an opening through which a lance is introduced for blowing oxygen into the charge within the vessel. In the past, a lance having a single orifice has been successfully employed in basic oxygen furnaces of relatively low capacity such as furnaces capable of producing heats up to 150 tons; however, in basic oxygen furnaces of greater capacity, it has not been possible to obtain designed production with a single orifice lance sized to provide high oxygen flow rates commensurate with the quantity of the charge to permit complete blowing of the heat within relatively short periods of time obtainable by the basic oxygen furnace process.

It is accordingly an object of the present invention to provide a novel process of basic oxygen furnace steelmaking which makes it possible to obtain high production from large capacity basic oxygen furnaces.

Another object is to provide a novel process of basic oxygen furnace steelmaking employing a multi-orifice lance for introducing the oxygen into the furnace.

Other objects and features of the present invention will appear more fully from the following detailed description considered in connection with the accompanying drawing which discloses apparatus for use in performing the novel method provided by the present invention. It is to be expressly understood, however, that the drawing is designed for illustration only and not as an indication of th limits of the invention, reference for the latter purpose being had to the appended claims.

In the drawing, in which similar reference characters denote similar elements throughout the several views:

FIGURE 1 is a diagrammatic view of a basic oxygen furnace and oxygen lance for use in performing the novel method provided by the present invention;

FIGURE 2 is a three-dimensional view of the discharge end of the oxygen lance shown in FIGURE 1; and

FIGURE 3 is an elevational view, partly in section, of the discharge end of the oxygen lance shown in FIG- URE 2.

It is known from actual experience in practicing the basic oxygen furnace steelmaking process that the quantity of oxygen required to eflect the desired degree of refining may be calculated from the size of the charge when considering the composition of the charge and a reasonable oxygen utilization efiiciency and that an economical oxygen blowing time for the process may be obtained by introducing oxygen into the furnace at a rate of at least 60 cubic feet per minute per ton of charge. In actual operations, oxygen flow rates up to about 70 cubic feet per ton of charge have been employed and it is possible, providing other factors pertaining to the introduction of oxygen into the furnace and onto the charge which influence the blowing operation are properly established and controlled, to employ oxygen flow rates as high as 100 cubic feet per minute per ton of charge; the latter oxygen flow rate is believed to be the highest practical 3,323,906 Patented June 6, 1967 rate of oxygen input to a basic oxygen furnace because, at higher oxygen inputs, the reaction would proceed so rapidly the scrap would not melt completely within the period of refining as established by the rate of oxygen input. While oxygen inputs of 60 to cubic feet per minute per ton of charge have actually been used or are theoretically possible, use of such flow rates even in the lower half of the range have not been successfully achieved in actual operations with basic oxygen furnaces of high capacity. This has resulted from problems attendant the introduction of high rates of oxygen flow onto and into the bath.

The physical characteristics of the jet of oxygen discharged from the lance downwardly toward the charge determines the manner in which the basic oxygen furnace process proceeds and influences many production controlling factors including efiiciency of oxygen utilization, completeness of and the time required for removal of impurities, and the maintaining of clean blowing, that is, the blowing of oxygen with minimum sparking, splashing and slopping. While the characteristics of the oxygen jet have varied influence upon the process, the area of impingement of the oxygen jet onto the metal bath and the impact pressure of the oxygen jet are of primary importance. Without an adequate area of impingement, it is diflicult if not impossible to obtain a high order of efiiciency and the impact pressure must be sufiicient to cause the jet of oxygen to adequately penetrate the bath to provide good mixing to prevent excessive sparking and splashing without slopping and yet preclude excessive penetration that would result in damage or abnormal erosion of the bottom refractories of the vessel. The area of impingement of the oxygen jet on the bath and the impact pressure of the oxygen jet are determined by the diameter of the discharge nozzle of the lance, the pressure of the oxygen fed to the lance and the height of the discharge end of the lance above the surface of the bath. For high rates of oxygen input, it has not been possible to correlate the foregoing parameters in such a manner as to obtain and maintain optimum areas of impingement and optimum impact pressures of the oxygen jet with the use of a single orifice [lance and this inability has not made it possible, in actual experience, to obtain production from high capacity furnaces which approaches the production that would be expected based on operation of the basic oxygen steelmaking process with furnaces of relatively low capacity.

Application of basic oxygen furnace techniques which have proven successful in furnaces of relatively low capacity below about tons, has been found from actual experience not to be adequate when properly correlated for high capacity furnaces, that is, the use of a single orifice lance having an enlarged nozzle diameter to provide the high rates of oxygen input for the large tonnages of charge involved. As noted above, in order to approach the low order of oxygen blowing time that has been obtained with low capacity vessels, it is necessary to blow oxygen into the vessel at the rate of at least 60 cubic feet per minute per ton of charge, and in actual experience with a 300 ton capacity basic oxygen furnace employing a single orifice lance of a nozzle diameter of 4.75 inches, it was found impossible to blow oxygen at the rate of 60 cubic feet per minute per ton of charge without excessive sparking, splashing and slopping which not only decreased the efiiciency of the operation requiring an abnormally long blowing time with increased oxygen consumption but further increased the time per heat because of the necessity to deskull the hood which is located above the vessel as well as the area surrounding and located beneath the furnace. On the other hand, when operating the 300 ton furnace with an oxygen input rate lower than 60 cubic 3 feet per minute per ton of charge to obtain clean blowing conditions, the time of the blow increased and the oxygen utilization eificiency decreased and there was experienced a lower scrap melting efiiciency because of insufiicient oxygen input and inadequate mixing of the bath. Further, in either event, an extremely low lining life, particularly the life of the refractory lining above the level of the bath, was experienced. It will be appreciated, of course, that the increase in blowingtime per heat, the inefiiciency of the process, the low lining life and the deskullingrequirements are factors which increase the total elapsed time between the tapping of successive heats and thus all combine to decrease the production of the furnace. It is believed that the foregoing difiiculties resulted from the fact that a single orifice lance having a large nozzle diameter required for the high rates of oxygen input could not be located with its discharge end spaced above the surface of the bath so as to be within an optimum range of lancebath distances because of limitations placed on penetration of the oxygen jet due to the depth of the bath and further because the impingement area of the oxygen jet on the surface of the bath was no greater than about 0.85% of the area of the bath. The low order of impingement area resulted from the physical characteristics of the oxygen jet produced by the large diameter single orifice and also from the fact the distance between the lance and the surface of the bath could not be increased to provide an optimum area of impingement without decreasing the depth of penetration of the oxygen jet to such a low value as would preclude efficient operation and without locating the discharge end of the oxygen lance a sufficient distance below the nose of the furnace to prevent damage to the nose refractories.

It has been discovered that the requirements of the oxygen jet necessary for optimum production, particularly the area of impingement of the oxygen jet on the surface of the bath and the impact pressure of the oxygen jet, may be obtained with high rates of oxygen flow necessary for efiicient operation of high capacity furnaces, by employing a lance including at least three orifices in combination with a vessel having specific geometric characteristics and by maintaining a critical relationship between the oxygen flow and the total orifice area of the lance;

In FIGURE 1 of the drawing, there is diagrammatically shown a basic oxygen furnace installation including a basic oxygen furnace and an oxygen lance 11 for use in practicing the method of the present invention. The furnace 10 includes an outer steel shell 12 and an internal refractory lining 13 and may be further defined as including a bottom section 14 which may be in the form of a surface of a sphere, a barrel section 15 which may be in the form of a cylinder and a nose section 16 of generally conical shape terminating in an opening 17 at the top of the furnace. The oxygen lance 11 is supported by any suitable means, not shown, in a vertical position With its longitudinal axis substantially coincident with a vertical axis passing through the center of the furnace 10 and is movable heightwise relative to the furnace including downward movement through the opening 17 to within the furnace as illustrated in the drawing and upward movement to a position in which its discharge end is located above the top of the furnace to permit the furnace to be tilted about supporting trunnions, not shown. The furnace is provided with a tap hole 18 located in the nose section 16 adjacent the lower end of the nose section where it merges with the upper end of the barrel section 15 to permit tapping of the furnace upon rotation of the furnace in a clockwise direction as viewed in the drawing. The lance 11 is fed with pressurized gaseous oxygen at its upper end through a conduit 19 and is cooled by any suitable coolant such as water entering the lance through conduit 20 and being discharged through conduit 21. As shown in FIGURES 2 and 3, the lance is of the multiorifice type including three discharge orifices 22, 23 and 24 located in the discharge end 25 of the lance; however, as described below, the method provided by the present invention may be practiced by utilizing a lance including more than three orifices. The orifices 22, 23 and 24 are preferably spaced about the longitudinal axis of the lance and may be fed from a common oxygen inlet conduit 26 and the orifices are inclined outwardly with respect to the longitudinal axis of the lance at an angle Within the range of 6 to 15, preferably at about 10 as shown. The space between the outer wall 27 of the lance and the oxygen conduit 26 may be divided by a cylindrical member 28 to provide annular passageways 29 and 30 for the inflow and outflow of coolant liquid, respectively.

The method provided by the present invention has particular application with basic oxygen furnaces of ton to 300 ton capacity in which the volume of the furnace is at least equal to 20 to 30 cubic feet per ton of charge and in which the H/D ratio falls within the range of 1.2 to 1.75; wherein, as shown in FIGURE 1, H comprises the inside vertical dimension of the vessel between the bottom and the opening 17 measured along the central vertical axis and D comprises the inside diameter of a newly lined vessel measured approximately at a mean height of the barrel section 15. The preferred H /D ratio is 1.5 for a vessel having H equal to 36 feet and D equal to 24 feet.

It will be appreciated that vessels of a capacity of 150 to 300 tons may be designed to possess H /D ratios less than 1.2 or greater than 1.75 however, it has been determined that optimum operation may be achieved when the H/D ratio falls within the range of 1.2 to 1.75 for furnaces of such capacity while employing a multi-orifice lance and maintaining a critical relationship between oxygen flow and orifice area. Specifically, it has been determined from actual operating experience that the ratio of oxygen flow to total orifice area should equal a number falling within the range of 1200-3000. The present invention may bepracticed employing multi-orifice lances including converging-diverging nozzles, converging-straight nozzles or smooth bore nozzles. Converging-diverging and converging-straight nozzles have particular application in, but not limited to, operations with deep baths and rates of oxygen flow at the low end of the oxygen flow range of 9,000 to 30,000 cubic feet per minute while smooth bore nozzles are preferable in, but not limited to, operations in which factors including the depth of bath make it dilfcult to maintain the depth of penetration within the maximum limit for rates of oxygen fiow within the high end of the range. Preferably, the smooth bore nozzles should be of a length at least equal to twice the diameter of the nozzle to obtain good configuration and stability of the jet. It has been further determined from actualoperating experience that with multi-orifice lances including smooth bore nozzles the ratio of oxygen flow to total orifice area should equal a number falling within the range of 1200-1600 and, when converging-diverging nozzles or converging-straight nozzles are used, the ratio should fall within the overall range of 12003000. The range of total nozzle area in square inches required to satisfy the foregoing relationship for different rates of oxygen flow in standard cubic feet per minute are shown in the following tables, Table A relating to smooth bore nozzles and Table B relating to converging-diverging and converging-straight nozzles in which the area is measured at the throat of the nozzles:

TABLE A.SMOOTH BORE NOZZLES Total nozzle area,

Oxygen flow rate, c.f.m. square inches Total nozzle area, Oxygen flow rate, c.f.m. 1 square inches 24,000 20.0-15.0 28,000 23.3-17.5 30,000 25.0-18.8

TABLE B.CONVERGING-DIVERGING AND CONVERG- ING-STRAIGHT .NoZZLEs Total nozzle area,

Oxygen flow rate, c.f.m. square inches Individual Nozzle Area, Square Inches en Flow Rate c.f.m.

Xyg Three Four Five Six Orifiees Orifiees orifices Orifices TABLE D.-CONVERGING-DIVERGING AND CONVERG- ING-STRAIGHT NOZZLES Individual Nozzle Area, Square Inches 0 en Flow Rate, c.f.m.

Xyg Three Four Five Six Orifices On'fices Orifiees Orifices The oxygen flow rate will vary depending upon the capacity of the furnace in accordance with the range of 6 to 100 cubic feet per minute per ton of charge. Thus. for furnace capacitance of 150 tons to 300 tons to which the method provided by the present invention is applicable, at the rate of 60 cubic feet per minute per ton of charge, the oxygen fiow rate would vary from 9,000 to 18,000 cubic feet per minute and, for the rate of 100 cubic feet per minute per ton of charge, the oxygen flow rate would vary from 15,000 to 30,000 cubic feet per minute with the overall range being 9,000 to 30,000 cubic feet per minute.

The feature of the present invention of blowing oxygen into a furnace having an H/D ratio within the range of 1.2 to 1.75 and a capacity of 150 to 300 tons by means of a multi-orifice lance and by maintaining the ratio of oxygen flow to total orifice area equal to a number within the range of 1200-3000 makes it possible to blow high rates of oxygen commensurate with the size of the charge While obtaining optimum impingement area between the oxygen jet and the surface of the bath and an oxygen jet of optimum impact pressure to obtain proper penetration of the oxygen jet into the bath for effecting adequate mixing of the bath with minimum sparking and splashing while preventing slopping and abnormal damage to the refractory lining. In furnaces of a capacity of 150 tons to 300 tons and having an H/D ratio of 1.2 to 1.75, the bath depth will preferably vary between 50 inches and 75 inches, the latter limit being established by scrap melting requirements and, by blowing oxygen with a multi-orifice lance in accordance with the foregoing relationship of oxygen flow and orifice area. It is possible to obtain depths of penetration of the oxygen jet varying from about onethird to about one-half the bath depth with an area of impingement of the oxygen jet equal to 3% to 5% of the area of the bath which is essential for efiicient operation of the process. The foregoing may be obtained with the discharge end of the lance spaced 40 to inches above the quiescent surface of the bath so as to locate the discharge end a sufiicient distance above the bath for high lance life and spaced sufficiently below the nose of the furnace to prevent damage to the nose refractories.

As mentioned above, basic oxygen furnaces of high capacity in the order of tons to 300 tons may be constructed to possess an H/D ratio less than 1.2 or greater than 1.75. High capacity vessels having an H/D ratio less than 1.2 will result in a shallow bath depth making it difiicult if not impossible to obtain adequate penetration with high rates of oxygen flow and hence an efficient and a clean blowing process essential for high production rates. On the other hand, high capacity furnaces having an H /D ratio in excess of 1.75 will result in high bath depths presenting scrap melting problems which increase the time of the oxygen blow and hence oxygen consum tion. The concept of employing vessels in basic oxygen furnace operations having an H /D ratio within the range of 1.2-1.75 obtains additional advantages. As noted above, the volume of basic oxygen furnaces is related to capacity, at least 20 to 30 cubic feet being required per ton of charge. Since H/D ratios of 1.2 to 1.75 are not far removed from the H/D ratio of unity in the case of a sphere, the weight of refractory material required to line a furnace of given capacity having an H/D ratio in accordance with the present invention is less than what would be required in a furnace of the same capacity but possessing a higher H/D ratio. In adition, furnaces of relatively low H/D ratio within the range provided by the present invention inherently require the nose section of the furnace to be inclined inwardly at a relatively shallow angle with respect to the horizontal. Thus, as seen in FIGURE 1, as the furnace is tapped, the portion of the nose extending away from the tap hole 13 toward the opening 17 provides an effective dam which tends to prevent the flow of slag and metal from the furnace through the opening 17 and permits performing of the tapping operation with relative ease as compared to a vessel having a high H/D ratio in which the nose section would be inclined at a steep angle with respect to the horizontal. In View of the size and great mass of the equipment and metal involved, this feature makes it possible to effect the tapping operation within a minimum period of time thereby further reducing the time of each heat. Furthermore, furnaces having relatively low H/D ratios simplify and thus make it possible to rapidly sample the bath and also result in a substantial reduction in the overall capital investment in erecting a basic oxygen furnace shop. Vessels having a low H/D ratio may be more easily supported and may be tilted by less expensive mechanism requiring application of less power. Also, employing vessels of low H/D ratio influences the construction cost of other components of the shop including the hood and reduces the overall height of the supporting structure.

The methods provided by the present invention have been practiced in a 300 ton basic oxygen furnace having an H/D ratio of 1.39 in which H equals 30 feet and D 7 equals 21.67 feet. In operation, the furnace was tilted and charged with scrap and hot metal and then returned to its vertical position and the oxygen lance lowered to Within the furnace as shown in FIGURE 1. The oxygen blow was then begun while charging slag forming fluxes to the furnace and after the slag was formed the oxygen was blown to effect the refining. The Table E includes information on two actual heats which are representative of the performance obtained employing a lance including three smooth bore nozzles each of a diameter of 2.75 10 inches and disposed 120 with respect to each other about the longitudinal axis of the lance and inclined outwardly at an angle of 10 from the latter axis:

TABLE E Heat A Heat 13 Charge:

Scrap (lbs.) 221,800 227,704 H013 metal (lbs.) 468, 000 474,000 Total metal charged (lbs.) 689, 800 701, 704 Ladle additions (lbs.) 3, 650 3, 440 Total metal (lbs. 693,450 705,144 Ingots produced (lbs 630,400 619,100 Scrap produced (lbs 6,934 7, 068 Loss (lbs.) 56,116 78,976 Yield (percent) 90.91 87.80 Oxygen pressure 175 225 Oxygen flow (cu. ft. 24, 000 23, 000 0g blowing time (min.) 22 25 Oz per ton 1, 736 1, 770 Time from charge to tap (min.) 31 36 Following the blowing operation in each of the above heats, a sample of the metal was analyzed and found to have the following composition (the balance being substantially iron) TABLE F Heat; A Heat B The 300 ton basic oxygen furnace was operated with a lance including three converging-diverging nozzles each of a diameter of 2.00 inches and disposed 120 with respect to each other about the longitudinal axis of the lance and inclined outwardly at an angle of 10 from the latter axis. Table G includes information on two actual heats which are representative of the performance ob tained with the discharge end of the lance positioned about inches above the surface of the bath:

TABLE G Heat 0 Heat D 60 166,000 156,250 513, 800 533, 000 680,820 688, 050 8,648 3, 627 Total metal (lbs.)"--- 684,468 691, 677 Ingots produced (lbs.) 614, 600 605, 000 Butts produced (lbs.) 10, 400 Scrap produced (lbs.) 7, 107 6, 917 Loss (lbs.) 52,361 79, 760 Yield (percent). 89. 79 87. 47 Oxygen pressure (p 200 200 Oxygen flow (cu. ft. per 23, 000 23,000 Oz blowing time (min.) 22.75 21.3 02 per ton 1, 820 1, 713 Time From Charge to Tap (min) 46 35 Following the blowing opertion in each of the above heats, a sample of the metal was analyzed and found to 7 have the following composition (the balance being substantially iron):

The average time from tap to tap on successive heats is about 50 minutes with about 4 minutes required for draining slag after tapping, about 1 minute for charging the scrap, about 2 minutes for charging hot metal, about 25 minutes for blowing oxygen, about 8 minutes to adjust the temperature and chemical composition of the bath, about 6 minutes to effect tapping and with about 4 minutes of miscellaneous delays. The production of the furnace averages over 240,000 ingot tons per month which exceeds the designed production of 230,000 ingot tons per month and the lining life averages over 300 heats. In prior operations of the same furnace employing a single orifice lance having a nozzle diameter of 4.75 inches, the greatest monthly production was less than 130,000 ingot tons and the lining life was heats, maximum.

Although only one embodiment of the invention has been disclosed and described herein, it is to be expressly understood that various changes and substitutions may be made therein without departing from the spirit of the invention as well understood by those skilled in the art. Reference therefore will be had to the appended claims for a definition of the limits of the invention.

What is claimed is:

1. Method of operating a basic oxygen furnace of the type including a refractory lined vessel having a bottom section, a barrel section and a nose section converging inwardly toward the central vertical axis of the vessel to form an opening through which an oxygen lance may be introduced,

the vessel having a capacity of 150 to 300 tons and possessing internal dimensions providing a volume of 20-30 cubic feet per ton of charge and an H/D ratio within the range of 1.2 to 1.75 and the lance having at least three discharge nozzles symmetrically positioned about the longitudinal axis of the lance and each nozzle having a discharge path disposed at an angle of about 6 to 15 relative to the longitudinal axis of the lance,

comprising the steps of charging the vessel with scrap and hot metal and thereafter introducing the lance through the opening to within the furnace with the longitudinal axis of the lance in substantial alignment with the central vertical axis of the vessel and with the discharge paths of the nozzles facing downwardly toward the bottom section of the vessel,

feeding pressurized gaseous oxygen to the lance at a rate of 9,000 to 30,000 cubic feet per minute and jetting oxygen from the discharge nozzles of the lance downwardly onto and into a bath of molten metal formed from the charge and contained within the lower portion of the vessel while maintaining the discharge nozzles of the lance spaced from 40 to 1-25 inches above the surface of the bath,

maintaining the ratio of oxygen flow in cubic feet per minute into the vessel to the total area in square inches of the discharge nozzles of the lance equal to a number Within the range of 12004000,

and maintaining the oxygen flow from the discharge nozzles of the lance from 60 to 100 cubic feet of oxygen per minute per ton of charge.

2. Method of operating a basic oxygen furnace as defined in claim 1 including the step of maintaining the area of impingement of the oxygen jetted from the discharge nozzles on the bath within a range of from 3% to 5% of the total area of the bath.

3. Method of operating a basic oxygen converter as defined in claim 2 including the step of maintaining the depth of penetration of the jetted oxygen into the bath from one-third to one-half the depth of the bath.

4. Method of operating a basic oxygen furnace of the type including a refractory lined vessel having a bottom section, a barrel section and a nose section converging inwardly toward the central vertical axis of the vessel to form an opening through which an oxygen lance may be introduced,

the vessel having a capacity of 150300 tons and including internal dimensions providing a volume of 2030 cubic feet per ton of charge and an H/D ratio within the range of 1.2 to 1.75 and the lance including at least three smooth bore discharge nozzles symmetrically positioned about the longitudinal axis of the lance and each having a discharge path disposed at an angle of about 6 to 15 relative to the longitudinal axis of the lance,

comprising the steps of charging the vessel with scrap and hot metal and thereafter introducing the lance through the opening to within the furnace with the longitudinal axis of the lance in substantial alignment with the central vertical axis of the vessel and with the discharge paths of the nozzles facing downwardly toward the bottom section of the vessel,

feeding pressurized gaseous oxygen to the lance at a rate of 9,000 to 30,000 cubic feet per minute and jetting oxygen from the discharge nozzles of the lance downwardly onto and into a bath of molten metal formed from the charge and contained within the lower portion of the vessel while maintaining the discharge nozzles of the lance spaced from 40 to 125 inches above the surface of the bath,

maintaining the ratio of oxygen flow in cubic feet per minute into the vessel to the total area in square inches of the discharge nozzles of the lance equal to a number within the range of 1200-1600,

and maintaining the oxygen flow from the discharge nozzles of the lance from to 100 cubic feet of oxygen per minute per ton of charge.

References Cited UNITED STATES PATENTS 2,741,555 4/1956 Cuscoleca et al -z --60 2,803,534 8/1957 Cuscoleca et a1 7560 3,170,016 2/1965 Grace 7560 3,195,875 7/1965 Mummert 26636 FOREIGN PATENTS 712,214 7/1954 Great Britain.

737,005 9/ 1955 Great Britain.

761,657 11/ 1956 Great Britain.

BENJAMIN HENKIN, Primary Examiner. 

1. METHOD OF OPERATING A BASIX OXYGEN FURNACE OF THE TYPE INCLUDING A REFRACTORY LINED VESSEL HAVING A BOTTOM SECTION, A BARREL SETION AND A NOSE SECTION CONVERGING INWARDLY TOWARD THE CENTRAL VERTICAL AXIS OF THE VESSEL TO FORM AN OPENING THROUGH WHICH AN OXYGEN LANCE MAY BE INTRODUCED, THE VESSEL HAVING A CAPACITY OF 150 TO 300 TONS AND POSSESSING INTERNAL DIMENSIONS PROVIDING A VOLUME OF 20-30 CUBIC FEET PER TON OF CHARGE AND AN H/D RATIO WITHIN THE RANGE OF 1.2 TO 1.75 AND THE LANCE HAVING AT LEAST THREE DISCHARGE NOZZLES SYMMETRICALLY POSITIONED ABOUT THE LONGITUDINAL AXIS OF THE LANCE AND EACH NOZZLE HAVING A DISCHARGE PATH DISPOSED AT AN ANGLE OF ABOUT 6* TO 15* RELATIVE TO THE LONGITUDINAL AXIS OF THE LANCE, COMPRISING THE STEPS OF CHARGING THE VESSEL WITH SCRAP AND HOT METAL AND THEREAFTER INTRODUCING THE LANCE THROUGH THE OPENING TO WITHIN THE FURNACE WITH THE LONGITUDINAL AXIS OF THE LANCE IN SUBSTANTIAL ALIGNMENT WITH THE CENTRAL VERTRICAL AXIS OF THE VESSEL AND WITH THE DISCHARGE PATHS OF THE NOZZLES FACING DOWNWARDLY TOWARD THE BOTTOM SECTION OF THE VESSEL, FEEDING PRESSURIZED GASEOUS OXYGEN TO THE LANCE AT A RATE OF 9,000 TO 30,000 CUBIC FEET PER MINUTE AND JETTING OXYGEN FROM THE DISCHARGE NOZZLES OF THE 